Orthogonal dipole antennas

ABSTRACT

A drooping dipole antenna having a center combination supporting mast and indicator balun structure with the drooping dipoles electrically close to the ground and part of the guy support system for the antenna effective primarily in the skywave mode of operation, but also producing a useful vertically polarized surface wave component with the droop of the dipole elements. Further, with two of these antennas colocated in an orthongonal configuration and the two antennas substantially at right angles sufficient mutual isolation is advantageously attained that the two input terminals are connectable simultaneously to two transmitters, two receivers, or one transmitter and one receiver.

[72] Inventors Warren B. Bruene;

Ross L. lBell, both of Dallas, Ten. [21] Appl. No. 17,239 [22] Filed Mar. 6, 1970 [45] Patented Nov. 2, 19711 [73] Assignee Collins Radio Company I Cedar NapidsJlowa V F [54] ORTHOGONAIL DIPOLE ANTENNAS 15 Claims, 14 Drawing Figs. [52] US. Cl 343/747, 343/797, 343/821, 343/861, 343/884 51 rm. Cl lllllq 21/26 [50] Field of Search 343/725, 747, 752, 797, 809, 821, 862, 884, 861 [56] References Cited UNITED STATES PATENTS 2,847,670 8/1958 Cox 343/821 3,521,286 7/1970 Kuecken 343/747 OTHER REFERENCES Microwave Journal, Oct. 1964, p. [7, copy 343- 809 Parten, CQ, Dec. 1966, p. 69 & 70 Copy 343- 886 Primary Examiner-Eli Lieberman Attorneys-Warren H. Kintzinger and Robert J. Crawford ABSTRACT: A drooping dipole antenna having a center combination supporting mast and indicator balun structure with the drooping dipoles electrically close to the ground and part of the guy support system for the antenna effective primarily in the skywave mode of operation, but also producing a useful vertically polarized surface wave component with the droop of the dipole elements Further, with two of these antennas colocated in an orthongonal configuration and the two antennas substantially at right angles sufficient mutual isolation is advantageously attained that the two input terminals are connectable simultaneously to two transmitters, two receivers, or one transmitter and one receiver.

PATENTED NUVZ N SHEET 3 [IF 6 FIG. 8

SYSTEM R F TEST CONN COMMUNICATION CENTRAL WVE/VTORS WARREN B. BIPUE/VE R055 L. BELL HDIH PATENTED NW2 1% SHEET w UF 6 m oI l/VVE/VTORS. WAR/PEN B. B/PUE/VE R055 L. BELL ma 9 i m5o 18 ATTORNEY PATENTEU NBVZ Ian 3,' 18, 1 Q5 SHEET 5 BF 6 lA/VE/i/TO/FS. WARREN B. Mum/5 R055 L. BELL ATTORNEY 11 ORTIBIUGGNAIL DIPOLE ANTENNAS This invention relates in general to antenna systems, and in particular, to dipole antennas having a center combination supporting mast and inductor balun structure for primarily a skywave mode of operation, but also producing a useful vertically polarized surface wave component, and in a two dipole orthogonal configuration two electrically isolated dipole antennas operational independently with the two input terminals connectable simultaneously to two transmitters, two receivers, or one transmitter and one receiver.

Many preexisting short-range HF communications systems have relied on surface wave propagation in the accomplishment of the communications mission generally through the use of vertically polarized whip antennas. A portion of the signal radiated from a vertical whip is propagated along the surface of the earth and is received by a similar antenna some distance away with the distance the signal can be received dependent on such factors as path attenuation, transmitter power, receiver sensitivity, antenna efficiency, terrain masking, and noise. Some of these factors are related only to equipment including transmitter power, receiver sensitivity, and antenna efficiency, while others relating only to operating environment include path attenuation, terrain masking, and noise. With reference to path attenuation, if the ground were a perfect conductor, the field strength of the transmitted signal would vary inversely with distance from the transmitting antenna, but since the earth is not a perfect conductor the signal is subject to additional attenuation. Attenuation is increased as the conductivity of the ground decreases and as the operating frequency is increased. Further, many areas of the earth are covered with foliage, another factor materially increasing signal attenuation with, in some areas, surface wave communication over even as little as one or two miles being difficult in dense jungle. Military personnel in South East Asia have even found it impossible at times in some areas to tall: over distances as short as several hundred feet with vehicular and man-pack radios. Furthermore, groundwave signals deteriorate from predicted values when obstructions are located between the transmitting and receiving antennas with the presence of an obstruction causing some signal reflection and some signal diffraction over the obstruction. The relative magnitude of these effects depends on the height of the obstruction and the steepness of the sides of the obstruction. Thus, surface wave signal propagation in hilly and mountainous areas produces field strength variations resulting from both interference patterns and from shadowing.

Noise originating from a number of sources is received on HF antennas, along with the desired signal, deteriorates the intelligence of the signal. These harmful noise sources include local man made noise, atmospheric noise originating from distant locations, and local thunderstorm activity. Man made noise is noteworthy in that it is predominately vertically polarized, and therefore, more efficiently received on vertically polarized antennas. This is a serious problem in deterioration of groundwave signal reception particularly in areas of activity involving use of machinery. Atmospheric noise, however, is derived from a number of sources including sunspot activity, transmissions from unwanted HF transmitting sources, and from remotely located thunderstorm areas. it is significant that noise from distant sources is usually much more pronounced at low elevation angles since propagation at higher angles requires more hops and consequently is subject to more path attenuation. Thus, it follows that since groundwave propagation requires radiation on or about the horizon and at low elevation angles, the amount of atmospheric noise received is greater than that received with higher angle radiation patterns. With respect to thunderstorm activities, it is interesting to note that they are more predominately located in the equatorial regions and that, therefore, the noise factor generated in this manner extending into the HF band is, generally, of greater significance as the location of operation is moved toward the equatorial regions.

It is, therefore, a principal object of this invention to provide an antenna system having a primary mode of communications substantially independent of local ground characteristics and terrain, and assurance that wherever in the world the antenna system were deployed the communication range would remain essentially constant.

Another object is to provide an antenna system with two electrically mutually substantially isolated dipole antennas supported above a ground plane operating as two independent antennas.

A further object with such an antenna system is to achieve a skywave mode of operation that is essentially omnidirectional for both colocated antennas of an orthogonal antenna particularly with the high-angle skywave signal propagation.

Still a further object is to provide an antenna system that, while having radiation patterns beamed primarily upward toward the ionosphere, the antenna dipoles produce a useful vertically polarized surface wave component.

Another object is to provide such an antenna system with two sets of dipole elements disposed in orthogonal relation with substantially complete omnidirectional surface wave coverage allowing for communication with whip equipped man-pack and vehicle radios.

A further object is to provide a feed to balanced antennas with adjustable couplers that does not require changing of antenna element lengths or heights of elements above ground.

Still a further object is to provide an orthogonal antenna configuration of two independent coilocated antennas that can be fed separately but when used in the receive mode for signals eminating from a transmitting antenna system over short range skywave paths that the two received signals be uncorrelated to a high degree, and when the operating frequency is near the optimum skywave frequency the two received signals have essentially a negative one correlation coefficient. Please note in this regard that uncorrelated signals are necessary for providing good diversity signal system operational results with, of course a negative one correlation ideal for diversity systems in that while one signal is fading the other signal is at a maximum.

Features of the invention useful in accomplishing the above objects include a drooping dipole having a center combination two vertical tube mast and balun structure with opposite antenna wire elements part of a guy support system for the antenna. The effective longitudinal center of the radiating an tenna elements of each individual antenna and the combination mast and balun tubes are substantially coplanar in a vertical plane. Further, the drooping dipoles are electrically close to the ground and configured primarily for an effective relatively short range HF skywave mode of operation although, a useful vertical polarized component is developed with the drooping dipole radiating elements. Two of these independent antennas are also quite effectively colocated in an orthogonal configu' ration with the vertical plane of one substantially at an optimized mutually isolated right-angle orientation to the vertical plane of the other. Each antenna both individually and in a two antenna orthogonal configuration utilize a top mounted centerally located antenna tuning coupler with antenna feed generally to the balun top.

Specific embodiments representing what are presently regarded as the the best modes of carrying out the invention are illustrated in the accompanying drawings.

In the drawings:

FIG. ll represents a combination installation and schematic showing of a drooping dipole electrically close to the ground antenna with a center two tube supporting mast and balun structure topped by an antenna coupler and with opposite antenna wires tied to ground stakes with tag lines;

FIG. 2, two colocated antennas such as the antenna of FIG. 1 disposed at, substantially, right angles to each other with the center mast structures extended upward from a common electrically conductive ground plane support plate, and with the drooping dipole antenna wires also serving as buy wires for the antenna structure;

FIG. 3, a perspective view of the orthogonal antenna struc ture of FIG. 2, showing more detail;

FIG. 4, another drooping dipole antenna structure having many features in common with the antenna of FIG. 1, but with more frequency-tuning features provided;

FIG. 5, an orthogonal drooping dipole antenna structure with each of the colocated antennas thereof much the same as the antenna of FIG. 4 with a plurality of frequency-bandswitching switches in each antenna balun and additional tuning control detail;

FIG. 6, a partial schematic detail showing with RF and control leads extended up one tube of an antenna combination mast and balun structure such as employed with the antenna of FIG. 5;

FIG. 7, a partial schematic showing of antenna circuitry much the same as that of FIGS. 5 and 6 with a step tune inductive capacitive circuit switchable into and out of interconnect between each balun connection with a respective antenna wire element as the wire element goes through series resonance as the antenna is tuned higher in each balun switched frequency-tuning band;

FIG. 8, a partial schematic showing in more detail of an antenna embodiment such as shown in FIG. 7 with RF and discriminator wires housed in one leg and power for torque motors and tower balun shorting switches housed in the second balun leg;

FIG. 9, skywave mode signal waveforms sensed by the two respective right angle orthogonally oriented antennas in the receive mode illustrating the advantageous negative one correlation coefficient relation therebetween ideally suited for diversity reception;

FIG. 10, an alternate drooping dipole antenna configuration with other frequency tuning features from the embodiments of FIGS. 1,4,6, and 7;

FIG. 11, still another drooping dipole antenna structure with frequency selectivity provided via different tuning structural features;

FIG. 12, a balanced drooping dipole orthogonal antenna structure with arrowhead radiating elements;

FIG. 13, a balanced drooping dipole orthogonal antenna structure with triple wire radiating elements; and

FIG. 14, a balanced drooping dipole orthogonal antenna structure with two radiating elements of different lengths coextended from the same feed connection.

Referring to the drawings:

The drooping dipole structure 20 of FIG. 1 is shown to include a set of electrically conductive tubes 21 and 22 mounted in relatively closely spaced parallel relation to extend vertically upward from a conductive ground plane plate 23 that shorts the tubes 21 and 22 together at the bottom substantially at the ground plane. The tubes 21 and 22 are physically inter connected at the top by a top mounted antenna coupler structure 24 that includes a tuning capacitor 25 connected between the tops of the combination mast and balun tubes 21 and 22 and also an interconnect lead 26 extended from a feed coax center line 27 from the top thereof within tube 21 to the top of tube 22. While center conductor 27 of coax signal feed line 28 is shown to be extended upward alone through the tube 21 to the upper end thereof the coax line 28 itself could be extended to the top of tube 21. Electrically conductive radiating element antenna wires 29 and 30 extend outward and downward at substantially 180 degrees orientation one from the other in the planar sense and as combination guy and drooping dipole antenna radiating elements extend from connection to the tops, respectively, of tubes 21 and 22 to insulating elements 31 tied to guy wire or rope tag lines 32 that are anchored at their outer ends by ground stakes or anchors 33. Coax signal feed line 28 is connected to a transmitter or a receiver (neither shown) for transmit or receive as desired.

This is a drooping dipole antenna configuration with a center combination supporting mast and inductor balun structure particularly useful for relatively short range HF communication to the range of 100 to 300 miles via the skywave highangle skip mode of operation. Further, with the sloped combination guy and dipole antenna element wires a vertically polarized surface wave component is developed useful for communication with equipped man-pack and vehicle radios.

There is a need to be able to operate two transmitters, two receivers, or one transmitter and one receiver simultaneously from substantially one location with sufficient mutual isolation provided that cross modulation between transmitters or from transmitter to colocated receiver antenna is acceptable low. In order to attain such capability isolation wise selectivity in transmitter output filter and antenna system mutual isolation a two antenna orthogonal drooping dipole antenna structure 34 such as shown in FIG. 2 is provided. With this orthogonal antenna configuration two colocated antennas, with each such as the antenna of FIG. 1, are disposed in plan view at substantially right angles to each other. Components of this orthogonal two antenna structure duplicating those of the single drooping dipole antenna 20 of FIG. 1 are given the same numbers or primed numbers as a matter of convenience. Referring also to FIG. 3 the orthogonal drooping dipole antenna structure 34 is shown with additional detail from FIG. 2 with the combination mast and balun tubes 21 and 22 of one antenna structure longer than those of the other in order that one top mounted antenna coupler structure 24' may overlie the other at right angles thereto. Please note further, that the combination mast and balun tubes of one antenna must be substantially common to the vertical plane of that antenna and that the two antennas along with the baluns thereof be oriented with their respective vertical planes substantially at right angles to each other since mutual signal coupling therebetween is proportional to the cosine of the angle form ed when there is a departure from the optimized right angle relation therebetween.

These antenna systems are excellent tactical systems particularly suitable for short range communications in the 0- to 300-mile communications range via their primary skywave mode of operation. They are capable of operation anywhere in the world and are actually not excluded from operating in those parts of the world where environmental conditions prohibit the use of surface wave communications since the primary skywave mode of operation provides essentially the same communications range whether in dense jungle, mountainous regions, desert, or other poor earth regions, with this mode of operation, advantageously, independent of ground characteristics. Skywave mode communications in the range of 0 to 300 miles generally use ionosphere F layer propagation since it is the most stable and predictable with a system requirement via such usage of frequency capabilities ranging from approximately 2.9 to 12 MHz. based on factors of minimum and maximum FOTs (frequency of optimum traffic). As observed through a period of years, these limits have proven accurate to at least a percent realiability factor. This is with appropriate scales based on ray-path geometry using the F layer limits of 240 and 450 km. and Ionosonde date over a period of years substantiating such limits. Such 0- to BOO-mile range operation requires that the antenna provides elevation plane coverage of 44 percent to 90 percent above the horizon and it is shown that these new antenna configurations in their electronically close to the ground configuration provide such 44 to 90elevation plane coverage between the frequencies of 2.9 to 12 MHz. Actually operation below 2.9 MHz. is quite often possible with the presence of the D, E, and F layers of ionosphere, and occasionally, such skywave operation above 12 MHZ. is possible, so, the tunable frequency band operational capabilities extending from approximately 2 to approximately l5 MHz., such as readily attained with some of applicants new antennas, is highly desired.

Referring now to the drooping dipole antenna 35 embodiment of FIG. 4 components duplicating those of FIGS. 1 and 2 are given the same identification numbers, primed numbers where they are similar, and new numbers for entirely different components. In this embodiment in place of the interconnecting lead 26 of the FIG. 1 and FIG. 2 embodiments an adjustable loading capacitor 36 is provided with one side lead connected to the end of coax lead 27 at the top end of combination mast and balun tube 211 and the other capacitor 36 leads is connected to the top of combination balun mast and tube 22. Furthermore, a shorting frequency bandswitching switch 37 is connected between the combination mast and balun tubes 21 and 22 spaced upwardly at a distance above the ground plane and shorting plate 23 such as to alter the frequency-tuning band range of the combination mast and balun and antenna structure to a higher frequency range when the switch 37 is closed to provide a conductive shorting path between the balun tubes Zll and 22 at that point. With these embodiments the individual antennas are fed in a balanced manner by virtue of, in effect, a 1:1 two-wire balun placed across the antenna terminals. Physically, in actuality the balun consists of two sets of tubing connected to the antenna wires at the top of the mast and with these sets of tubing being the vertical structural members of the mast. The two lengths of tubing in each antenna tubing set are shorted together at the lower end by the ground plate 23 or at an intermediate point by a shorting switch such as the band switching switch 37 of the FIG. 4 embodiment with the shorted together tubes being a shorted transmission line across the antenna feed point. Please note that at these feed points with respect to the respective antennas these shorted transmission lines appear as inductive susceptances balanced with respect to ground.

Referring now to FIG. 5, the two colocated orthogonal antenna structure 38 is shown to have, in place of one bandswitching switch 3'7 in FIG. 4i, three balun inductor switches 37a, 37b, and 37c that are actually enclosed within dielectric tubes. The bandswitching switches 37a, b, and 0, provide for progressively bandswitching from lower to higher frequency bands with the respective two mast tube and balun lines 21' and 22'. Please note the control line 39 extension from an antenna control signal box 40 that extends up tube 211' with the RF coax line M3 for each balun and mast two tube set. Further, the coupler antenna control source is provided with a primary power input line ill and witha control line 42 to control signal box. Circularly formed spacers 43 of dielectric material such as fiberglass are used as tube spacersin the antenna mastbalun structure.

Referring also to the schematic detail MG. 6 showing for one of the two coplanar antennas of the FIG. 5, orthogonal antenna structure 33. A group of control wires in control line 39 extends to the antenna coupler upward through tube 21 to the antenna coupler 24" and within the coupler structure 24 it includes wiring to discriminator circuit 44 and in cooperation with the wiring to the discriminator 44 wire from an interconnect system to tuning drive motor 45 for the .uning capacitor 25 and also to loading drive motor 46 for adjustment of loading capacitor 36'. Other control wires of line 39 are extended to switch actuating solenoids 47a, Mb, 47c for bandswitching control of balun shorting switches 37a, 37b, and 370.

This particular orthogonal dipole antenna system has two isolated colocated drooping dipole antennas supported by a combination mast and balun structure with one balun for each of the two antennas incorporated in the antenna structure. Basically the mast consists of four vertical tubular sections each made up of four aluminum tubes arranged in substantially a square configuration and maintained in position by glass-reinforced plastic spacers located at various vertically spaced locations therealong. Four radiating elements also serve as guys for the mast and balun structure and are so choosen as to have high mechanical strength as well as good electrical conductivity. These radiating elements are physically attached adjacent the tops of respective tubes in the combination mast and balun structure, and may be, for example, radiation elements of one quarter inch phosphor bronze cable 45 feet long. These in turn are connected individually each to an electrical insulator that in turn is connected via rope or additional cable to a ground anchor. The tow antenna couplers 24$", one for each antenna, are identical in construction with a discriminator circuit unit M contained therein, and motors 43 and M for driving the tuning capacitor 25' and the loading capacitor 36 therein. Please note, that heavy plastic tie plates are provided on the tops and bottoms of the two couplers M" thereby providing sufficient structural rigidity that no strain is placed on the capacitors 23 and 36'. Further, each coupler 24$" is enclosed in a high-impact dielectric plastic material cover, and the bottom tie plate of each coupler 24" is provided with mechanical fasteners of a conventional nature (detail not shown) for securing the couplers 24" to the tops of the respective antenna mast tubes. Please note again, that the two input terminals may be connected simultaneously to two transmitters, two receivers, or one transmitter and one receiver. This is made possible by the high natural isolation running to as much as 30 db. and more between the two antennas as is advantageously attained through the orthogonality configuration thereof. The two orthogonal drooping dipole antennas are effectively electrically close to ground over most of the 2 to 30 MHz. band and therefore generate upwardly directed radiation patterns admirably suited for the preferred sltywave mode of operation. Efficient operation is attained by placing the antenna couplers 2d" at the top of the mast at the feed points of the respective antennas. In doing so, and performing the impedance match at this feed point, little power is lost in the RF coax cable connected to the transmitter when the individual antennas are being used in the transmitted mode of operation.

Each antenna coupler 24" tunes the impedance of its antenna in the two antenna orthogonal antenna structure, along with the associated inductor-balun to provide a SO-ohm impedance 1.5:1 VSWR maximum to the transmitter connected thereto for the transmit mode of operation. The tuning operation of the coupler 24" is automatically controlled by the respective antenna coupler control 404 with each coupler containing two capacitor modules and a discriminator module and with the coupler enclosing case configuration being shaped to specifically minimize lRF coupling into the second channel, or other antenna, of the two antenna system. The tuning elements of each coupler are two variable capacitors with tuning control thereof much the same as has been employed in other antenna and coupler system product lines for shunt type antennas (complete detail not shown). During tuning the discriminator M in each coupler 24" senses the impedance of its associated antenna through the coupler and produces polarized DC output voltages proportional to the phase angle and the loading impedance magnitude. These phasing and loading voltages both go to a zero volt :null when the tuned impedance becomes 50 +j0 ohms. The phasing and loading voltages are fed to servo amplifiers in the control unit 40 that in turn drive the positioning motors for the two capacitors in the respective coupler 24". During tuning the loading capacitor 36' and the tuning capacitor 25' in the antenna coupler 24" for one of the antennas of the two antenna orthogonal antenna system produce an impedance of 50 +j0 with a 2:1 VSWR maximum at the coax line 28 center conductor 27 connection to the descriminator M. The tuning capacitor 25 is positioned by the descriminator loading voltage and zeroed to produce an inductive impedance with a 50-ohm series resistive component. The inductive reactance is series resonanted in phase by the loading capacitor 36' and the SO-ohm resistive load is produced. Capacitor 36 is positioned by the descriminator phasing voltage and servo drive to produce series resonance. Please note that loading capacitor 36' remains bypassed at frequencies when the associated antenna VSWR is low and with this capacitor not required for tuning at such times. Further, the switchable shorted length of the antenna inductor-balun supplements the tuning range of the associated tuning capacitor 25 and loading capacitor 36.

With reference to FIG. 7 a simplified schematic is presented of an alternate balanced antenna 48 having a combination mast and balun with a top mounted tunable antenna coupler structure 24" that is similar in many respects to the antenna structure of FIG. 6 and applicable for use in an orthogonal antenna structure such as that illustrated in FIG. 5. Again with antenna 48 those components the same or substantially the same as with the antenna structure of FIG. 6 are given the same or primed numbers. It is of particular interest to note that the antenna radiating elements 29' and 30 are switch signal coupled through an individual paralleled coil 49 and capacitor 50 circuit for each. That is, they are switchable into and out of interconnect between each respective balun connection and the respective antenna wire element 29' or 30 via individual shorting switches 51 being opened and closed. This is with the switching action taking place as the respective wire elements 29' and 30' go through series resonance as the antenna is tuned higher in each balun switched frequency-tuning band and the switches 51 being opened at the wire radiating elements go through the series resonant operational state. In FIG. 8 the antenna structure of 48 is shown in greater schematic detail than in FIG. 7 and additional component detail such as indicated in FIG. and some that is shown in the schematic of FIG. 6 is included with however some differences therefrom. Among differences with this embodiment the RF capacitor 50 circuits in the connection between the antenna a radiating elements 29' and 30 respective balun tubes tops.

Please note, that in this embodiment the insulator tie-on link blocks 53 provide electrical isolation between the antenna radiating elements 29' and 30 and tube top mechanical tie connective cables 54 fastened to the tops of the respective combination mast and balun tubes 21 and 22. This structure is required with the paralleled coil 49 and capacitor 50 circuits so they may be switched into the out of electrically conductive circuit state between the tops of the tubes 21 and 22 and the respective radiating elements 29 and 30'. Please note, the more specific inductor balun shorting switch 37b detail such 'as would be employed for the shorting switches 37a and 37b and, if there are more, 37c etc.

- Operational results are portrayed by the received signal level vs time tracing of FIG. 9 for both antennas of a structure such as shown in FIG. 5, or for that matter such as alternately shown in FIG. 3, with an appropriately tuned combination mast and balun and top mounted antenna coupler structure being used in the receive mode in Richardson, Tex. for a CW signal eminating from a transmitter operated in the skywave mode of operation at a location approximately 100 miles north of the orthogonal receiving antenna with atmospheric and ionospheric conditions as they existed at 1330 hours on Apr. 17, l969. Further, the colocated antennas of the two antenna orthogonal antenna receiving structure are located east and west, and north and south respectively with the receive signal being a CW signal of9.657 MHz. It is interesting to note and quite significant that the two received signals on the antennas of the orthogonal antenna structure are uncorrelated to a high degree in that while one signal is fading the other signal is at a maximum. This is particularly so with an operating frequency near an optimum skywave frequency, such as was the case here, with transmission over a 100-mile path the two received signals having advantageously, essentially a negative one correlation coefficient. Such a negative one correlation coefficient between the two received signals with one antenna sensed signal being a maximum as the other is a minimum is typified by the two respective antenna received signal recorded traces as the ideal situation antenna reception wise particularly for diversity reception.

With the embodiment of FIG. 10 another alternate approach is provided for tuning an antenna and balun system with a variable capacitor interconnecting the balun tube tops where components the same are numbered the same, and some much the same are given primed numbers, as their corresponding counterparts in the embodiments of FIGS. 1, 4, 6, or 7. In this embodiment the center conductor 27 extension from RF coax 28, connected to an RF translating system 55, is provided with a series of switches 56a, 56b, 560 or even more as the case may be. These switches may all be closed to, in effect, provide through feed to the top of the balun such as is the condition with the embodiment of FIG. 1 or they may be selectively thrown, individually, to selectively provide balun feed to different selected points vertically up the balun via switch completed crosstie connection feed lines 57a, 57b, and 570. This establishes cross feed from the respective feed-actuated switch 56a, 56b, 560 of line 27 to the opposite vertical combination mast and balun tube 22" instead of having the feed line 27' being closed all the way .up to the top of mast and balun tube 21" for cross connection there to the top of combination mast and balun tube 22". Here again shorting switches are provided with the balun to provide cross shorting paths in higher and higher frequency switch selected tuning bandwidths progressively via switches 37a, 37b, and 37c from the lowest frequency bandwidth with ground plane plate 23 being the shorting agent for the shorted balun transmission line configuration. With the shorted balun cross connections switchable as desired and the switches for varying the feed points of the balun, and with the variable capacitor 25, a very efficient highly flexible high Q inductor system is provided. This is with the balun being fed to provide impedance matching in bands, and where, when the system is resonated by capacitor 25, the impedance at the balun feed point being resistive. Please note that the value of resistance should be within the SWR matching range of the transmitter that may be, for example, a 3:1 SWR. This allows R to be any value from 16.7 to ohms with R-(L,1L,'RA Thus, it is possible to cover the lower HF range in bands such as 2-3.3-4 and 4-6 mc. etc., and the configuration hereby should be satisfactory for the entire 2 through 30 me. range with enough bands being provided although only four are provided for in the embodiment of FIG. 10. With this antenna employed in a coplanar relation with another such antenna to form an orthogonal antenna system the desired right-angle antenna projected planar configuration is readily maintained sufficiently well enough in the field to insure at least 25 to 30 db. of antenna mutual isolation. This is good enough mutual isolation that there should be little interaction between transmitters during tune up and little cross modulation between them. In fact such mutual isolation has proven good enough so that simultaneous transmission from one antenna and reception via the other is practical with only a fairly small frequency separation between the transmitting antenna and the receiving antenna required.

The balanced drooping dipole configuration of FIG. 11 is an alternate approach that is particularly well suited for use in an orthogonal antenna system where the antennas go resonant around 7 mo. and the feed becomes a low Q tuned balun with more selectivity thereby achieved. This is accomplished by reconfiguring to a tuned balun circuit with the RF line 28 center lead 27" extended from within the combination mast and balun tube 21" via cross feed line 570 through the wall thereof without electrical contact therewith to direct electrical connection with the combination mast and balun tube 22" at a location relatively closely spaced from the shorted bottom of the balun structure. In addition to this low balun feed point feature, such as would be attained in the embodiment of FIG. 10 by the throwing open of switch 56a to the cross feed line 57a, the tuned balun structure is provided at the top with inductive coaxially located lines 58 and 59 extended down within the tops of the combination mast and balun tubes 21" for a portion of the lengths thereof to an interconnection therebetween and through the walls of the tubes 21" and 22" by an interconnecting line 60. The antenna radiating elements 29" and 30" are directly connected to the tops of lines 58 and 59 without making electrical contact nunne rum with the tubes 2b and 222". This approach presents a very high selectivity factor such as may be desired for certain specific frequency ranges.

Referring now to the orthogonal antenna configuration of HG. l2 arrowhead-type radiating elements 29" and 30" are employed that are balanced with respect to each of the individual antennas thereof. The radiating elements 29" and 30 extend from respective tuned balun feed points in a drooping dipole configuration to arrowhead pointed outer ends thereof. Each shanlt 61 of each arrow head is tied by an intervening dielectric material rope 62 or like intervening insulator to the corresponding opposite shank 61 of the adjacent radiating element 29" or 3t)" of the other antenna. This helps insure theattainment of a square antenna configuration and maintains the desired right angle between the two antennas of the orthogonal antenna structure. Please note further, that the arrowhead V ends of elements 29" and 30", since they are a high-voltage high-power radiating points in the antenna structure, are terminated approximately nine feet above the ground for personnel safety. The points of the V ends of elements 29 and MI" are connected through insulators 31 and tie lines 32 to ground anchor stakes 33.

With the balanced drooping dipole orthogonal antenna structure of lFlG. til the individual antenna and antenna balun feed structures have top mounted antenna couplers 24", such as employed with the embodiment of FIG. 7 and fl, feeding radiating element structures 62 of a triple wire element configuration that being in a uniformly laterally electrically balanced relation are consistent with the attainment of the desired degrees of mutual isolation between the two right-am gled colocated antennas of an orthogonal antenna system. Please note that such triple wire radiating element structures 62 may be used with various other tuned balun structures hereinbefore described in addition to that of FIGS. 7 and 8.

With the embodiment of FIG. 11 lantenna radiating element structures 63 each include wires 64 and 65 of different lengths utilized in a balanced drooping dipole orthogonal antenna structure with such antenna radiating elements usable with any of the tuned combination mast and balun structures illustrated, and with these multiple radiating element structures 63 being of balanced length design from end to opposite end in each antenna and in right angles orthogonal antenna relation in the ground projected planar sense. It is interesting to note that at lower frequencies the longer wire elements will take the majority of feed energy with tuned resonance thereof, and as higher frequencies are achieved above a certain point the shorter elements attached to the same feed points will take the bulk of the energy as they are brought into resonance. Obviously, more than just two such various length radiating elements could be connected to individual feed points as long as they are in balanced relationship with respect to both sides or ends of each antenna. Further, please note that insulators 66 support the outer ends of the shorter radiating element wires 65 relative to or from the longer radiating element wires 64 that are also part of the guy wire system for the orthogonal antenna mast and balun structure. Relatively short tag lines 32, extended from insulators M to earth stakes 33, are provided with the structure just as have been indicated with various other embodiments presented hereinbefore.

Whereas this invention is here illustrated and described with respect to several specific embodiments thereof, it should be realized that various changes may be made without departing from the essential contributions to the art made by the teachings hereof.

We claim:

ll. An antenna with opposite radiation elements extended from a center feed section, wherein: said opposite radiation elements have longitudinally extended effective line centers of signal propagation effectiveness common to the same vertical plane and of substantially equal length; a combination mast and balun structure with two vertically extended parallel structural electrically conductive members mounted on a supporting conductive plate and with vertically elongate elecill tronically active centers common to said vertical plane; first variable capacitive means connected between said two vertical conductive structural mast-balun members; RF signal conductive line means connectable to RF signal translating means and extended up a portion of one of said two vertical mastbalun members and signal coupled across to positive signal feed conductive contact with the other of said two vertical mast-balun members; feed connective means for each of said opposite radiation elements with said mast-balun structure adjacent the top of each respective vertical mast-balun member; and with two of said antennas colocated in an orthogonal antenna structure wherein the vertical plane of one antenna is substantially at right angles to the vertical plane of the other antenna for optimized mutual isolation between the two colocated antennas of the orthogonal antenna structure; and wherein said RF signal conductive line means for each of the colocated antennas is extended to the top of a first one of the two vertical mast-balun members; and a second tunable capacitor is provided in a crossover signal feed connective means from the top of said RF signal conductive line means to said positive feed conductive contact to the second vertical mast-balun member of that antenna.

2. The orthogonal antenna structure of claim 1, with said first and second tunable capacitors of each of the colocated right-angle antennas are included in an antenna coupler structure mounted at the top of the combination mast and balun structure of the respective antenna.

3. The orthogonal antenna structure of claim 2 wherein the combination mast and balun structure of one colocated antenna is sufiiciently longer than the mast and balun structure of the other colocated antenna that the center bottom of the antenna coupler structure of one antenna overlies the center top of the antenna coupler structure of the other antenna.

l. An antenna with opposite radiation elements extended from a center feed section, wherein: said opposite radiation elements have longitudinally extended effective line centers of signal propagation effectiveness common to the same vertical plane and of substantially equal length; a combination mast and balun structure with two vertically extended parallel structural electrically conductive members mounted on a supporting conductive plate and with vertically elongate electronically active centers common to said vertical plane; first variable capacitive means connected between said two vertical conductive structural mast-balun members; RF signal conductive line means connectable to RF signal translating means and extended up a portion of one of said two vertical mastbalun members and signal coupled across to positive signal feed conductive contact with the other of said two vertical mast-balun members; feed connective means for each of said opposite radiation elements with said mast-balun structure adjacent the top of each respective vertical mast-balun member, wherein each of said two vertical mast-balun members are tubes of conductive material projecting upwardly in parallel effective inductive spaced relation; nonconductive dielectric structural means interconnecting said tubes in maintenance of the spaced relation of the tubes in a shorted transmission line balun structure; wherein said first variable capacitive means is connected between the tops of the tubes comprising said two vertical mast-balun members; said RF signal conductive line means is extended upward within a first tube of said mastbalun tubes; signal coupling means from said RF signal line across to positive signal conductive connection with the second tube of said mast-balun tubes as an RF signal feed point for the shorted transmission line balun structure at that location.

5. The antenna of claim 4, wherein said crossover feed point connection is to the top of said second tube.

6. The antenna of claim 5, wherein a second tunable capacitor is included in said signal coupling means from the RF signal line across to said second tube.

7. The antenna of claim 4, wherein said RF signal crossover feed point connection is to an intermediate point between the top and bottom of said second tube.

8. The antenna of claim 7, with a plurality of said crossover feed point connections on said second tube connected to a plurality of vertically spaced signal coupling means from said RF signal line, and with said crossover feed point connections spaced along said second tube between the bottom and top thereof; and with switch means included in said plurality of signal coupling means from said RF signal line for selectively switching the balun structure between the feed point locations as desired.

9. The antenna of claim 8, with at least one switchable shorting means connected between the two tubes of said combination antenna mast and balun structure intermediate the bottom and top thereof.

10. The antenna of claim 4, with a plurality of switchable shorting means connected between the two tubes of said combination antenna mast and balun structure at various locations intermediate the bottom and top thereof.

11. The antenna of claim 10, wherein control means is provided for said plurality of switchable shorting means; and said control means includes control wire connections to switch throw means with the control wires extending up said combination antenna mast and balun structure.

12. The antenna of claim 4, wherein a tunable antenna coupler is mounted at the top of the combination antenna mast and balun structure; antenna coupler control means is provided with tunable capacitor setting means included in the coupler; and with control system lines extended through said combination mast and balun structure from an external control source to the tunable antenna coupler.

13. The antenna of claim 12, wherein a paralleled coil and capacitor signal coupling circuit is provided in a connection between each radiating element and the associated tube top of the combination mast and balun two tube structure.

14. The antenna of claim 13, wherein shorting switch means is provided across each of said paralleled coil and capacitor signal coupling circuits for selectively switching the paralleled coil and capacitor signal coupling circuits into and out of signal coupling use between thev radiating elements and the respective combination mast and balun tube tops.

15. The antenna of claim 4, with the signal coupling means from said RF signal line across to positive signal conductive connective with the second tube of said mast-balun tube structure at a location intermediate the top and bottom thereof; and RF signal lines extended from a connection with respective radiating elements down through substantially are equidistant upper portion of respective tubes of the mast-tube balun structure to a cross conductive line connection therebetween through tube wall openings provided therefor.

l l I i Column Column Column Column Column Column Column Column Column Column (SEAL) ESt Patent No.

v u u u u l-FJDEJ'ARD HAT attesting Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated November 2, l97l Inventor(s) Warren B. Bruene and Ross L. Bell It is certified that error appears in the above-identified patent; and that said Let;

line 72, change Patent are hereby corrected as shown below:

"buy" to --guy--;

after "with" insert --whip-;

change "90" to --90-;

line 40, after "box" insert --40--; last line, change "tow" to --two--; line 27 line line line line Signed and Since there is a misalignment in the numbers set forth in this Certifi numerical line count from the top QETCIILSR, J1.

"transmitter" to --transmitters-; "at" to --'as-;

"(L lL RA" to --(L /L RA--;

"for" insert --and 22" change change change change before printed patent, the reference line cate of Correction are the actual of each column.

" "iled this 1 8th day of April 1 97.

April 18, 1972 l-iOBLIRT GOTTSCHALLI Commissioner of Patents QM F'O-lOSO (10-69) 

1. An antenna with opposite radiation elements extended from a center feed section, wherein: said opposite radiation elements have longitudinally extended effective line centers of signal propagation effectiveness common to the same vertical plane and of substantially equal length; a combination mast and balun structure with two vertically extended parallel structural electrically conductive members mounted on a supporting conductive plate and with vertically elongate electronically active centers common to said vertical plane; first variable capacitive means connected between said two vertical conductive structural mast-balun members; RF signal conductive line means connectable to RF signal translating means and extended up a portion of one of said two vertical mast-balun members and signal coupled across to positive signal feed conductive contact with the other of said two vertical mast-balun members; feed connective means for each of said opposite radiation elements with said mast-balun structure adjacent the top of each respective vertical mast-balun member; and with two of said antennas colocated in an orthogonal antenna structure wherein the vertical plane of one antenna is substantially at right angles to the vertical plane of the other antenna for optimized mutual isolation between the two colocated antennas of the orthogonal antenna structure; and wherein said RF signal conductive line means for each of the colocated antennas is extended to the top of a first one of the two vertical mast-balun members; and a second tunable capacitor is provided in a crossover signal feed connective means from the top of said RF signal conductive line means to said positive feed conductive contact to the second vertical mast-balun member of that antenna.
 2. The orthogonal antenna structure of claim 1, with said first and second tunable capacitors of each of the colocated right-angle antennas are included in an antenna coupler structure mounted at the top of the combination mast and balun structure of the respective antenna.
 3. The orthogonal antenna structure of claim 2 wherein the combination mast and balun structure of one colocated antenna is sufficiently longer than the mast and balun structure of the other colocated antenna that the center bottom of the antenna coupler structure of one antenna overlies the center top of the antenna coupler structure of the other antenna.
 4. An antenna with opposite radiation elements extended from a center feed section, wherein: said opposite radiation elements have longitudinally extended effective line centers of signal propagation effectiveness common to the same vertical plane and of substantially equal length; a combination mast and balun structure with two vertically extended parallel structural electrically conductive members mounted on a supporting conductive plate and with vertically elongate electronically active centers common to said vertical plane; first variable capacitive means connected between said two vertical conductive structural mast-balun members; RF signal conductive line means connectable to RF signal translating means and extended up a portion of one of said two vertical mast-balun members and signal coupled across to positive signal feed conductive contact with the other of said two vertical mast-balun members; feed connective means for each of said opposite radiation elements with said mast-balun structure adjacent the top of each respective vertical mast-balun member, wherein each of said two vertical mast-balun members are tubes of conductive material projecting upwardly in parallel effective inductive spaced relation; nonconductive dielectric structural means interconnecting said tubes in maintenance of the spaced relation of the tubes in a shorted tRansmission line balun structure; wherein said first variable capacitive means is connected between the tops of the tubes comprising said two vertical mast-balun members; said RF signal conductive line means is extended upward within a first tube of said mast-balun tubes; signal coupling means from said RF signal line across to positive signal conductive connection with the second tube of said mast-balun tubes as an RF signal feed point for the shorted transmission line balun structure at that location.
 5. The antenna of claim 4, wherein said crossover feed point connection is to the top of said second tube.
 6. The antenna of claim 5, wherein a second tunable capacitor is included in said signal coupling means from the RF signal line across to said second tube.
 7. The antenna of claim 4, wherein said RF signal crossover feed point connection is to an intermediate point between the top and bottom of said second tube.
 8. The antenna of claim 7, with a plurality of said crossover feed point connections on said second tube connected to a plurality of vertically spaced signal coupling means from said RF signal line, and with said crossover feed point connections spaced along said second tube between the bottom and top thereof; and with switch means included in said plurality of signal coupling means from said RF signal line for selectively switching the balun structure between the feed point locations as desired.
 9. The antenna of claim 8, with at least one switchable shorting means connected between the two tubes of said combination antenna mast and balun structure intermediate the bottom and top thereof.
 10. The antenna of claim 4, with a plurality of switchable shorting means connected between the two tubes of said combination antenna mast and balun structure at various locations intermediate the bottom and top thereof.
 11. The antenna of claim 10, wherein control means is provided for said plurality of switchable shorting means; and said control means includes control wire connections to switch throw means with the control wires extending up said combination antenna mast and balun structure.
 12. The antenna of claim 4, wherein a tunable antenna coupler is mounted at the top of the combination antenna mast and balun structure; antenna coupler control means is provided with tunable capacitor setting means included in the coupler; and with control system lines extended through said combination mast and balun structure from an external control source to the tunable antenna coupler.
 13. The antenna of claim 12, wherein a paralleled coil and capacitor signal coupling circuit is provided in a connection between each radiating element and the associated tube top of the combination mast and balun two tube structure.
 14. The antenna of claim 13, wherein shorting switch means is provided across each of said paralleled coil and capacitor signal coupling circuits for selectively switching the paralleled coil and capacitor signal coupling circuits into and out of signal coupling use between the radiating elements and the respective combination mast and balun tube tops.
 15. The antenna of claim 4, with the signal coupling means from said RF signal line across to positive signal conductive connective with the second tube of said mast-balun tube structure at a location intermediate the top and bottom thereof; and RF signal lines extended from a connection with respective radiating elements down through substantially are equidistant upper portion of respective tubes of the mast-tube balun structure to a cross conductive line connection therebetween through tube wall openings provided therefor. 